The Mantoux test (PPD) is the gold standard for diagnosis of infection with M. tuberculosis. While the test is neither sensitive nor specific, previous efforts at a better diagnostic test have been disappointing. In children, the distinction between asymptomatic infection and active disease with M. tuberculosis is also challenging. Several new antigens of M. tuberculosis have been identified and manufactured. We will study the antibody and T-cell responses to these antigens in children with no infection, asymptomatic infection or active disease with M. tuberculosis. We hope that one or more of the new antigens will be useful in developing a sensitive and specific assay for infection or disease with M. tuberculosis.